Enhancing grain shape, thermotolerance, and alkaline tolerance via Gγ protein manipulation in rice.

KEY MESSAGE: Our findings highlight a valuable breeding resource, demonstrating the potential to concurrently enhance grain shape, thermotolerance, and alkaline tolerance by manipulating Gγ protein in rice. Temperate Geng/Japonica (GJ) rice yields have improved significantly, bolstering global food security. However, GJ rice breeding faces challenges, including enhancing grain quality, ensuring stable yields at warmer temperatures, and utilizing alkaline land. In this study, we employed CRISPR/Cas9 gene-editing technology to knock out the GS3 locus in seven elite GJ varieties with superior yield performance. Yield component measurements revealed that GS3 knockout mutants consistently enhanced grain length and reduced plant height in diverse genetic backgrounds. The impact of GS3 on the grain number per panicle and setting rate depended on the genetic background. GS3 knockout did not affect milling quality and minimally altered protein and amylose content but notably influenced chalkiness-related traits. GS3 knockout indiscriminately improved heat and alkali stress tolerance in the GJ varieties studied. Transcriptome analysis indicated differential gene expression between the GS3 mutants and their wild-type counterparts, enriched in biological processes related to photosynthesis, photosystem II stabilization, and pathways associated with photosynthesis and cutin, suberine, and wax biosynthesis. Our findings highlight GS3 as a breeding resource for concurrently improving grain shape, thermotolerance, and alkaline tolerance through Gγ protein manipulation in rice.

Acclimation to warmer temperatures can protect host populations from both further heat stress and the potential invasion of pathogens.

Thermal acclimation can provide an essential buffer against heat stress for host populations, while acting simultaneously on various life-history traits that determine population growth. In turn, the ability of a pathogen to invade a host population is intimately linked to these changes via the supply of new susceptible hosts, as well as the impact of warming on its immediate infection dynamics. Acclimation therefore has consequences for hosts and pathogens that extend beyond simply coping with heat stress-governing both population growth trajectories and, as a result, an inherent propensity for a disease outbreak to occur. The impact of thermal acclimation on heat tolerances, however, is rarely considered simultaneously with metrics of both host and pathogen population growth, and ultimately fitness. Using the host Daphnia magna and its bacterial pathogen, we investigated how thermal acclimation impacts host and pathogen performance at both the individual and population scales. We first tested the effect of maternal and direct thermal acclimation on the life-history traits of infected and uninfected individuals, such as heat tolerance, fecundity, and lifespan, as well as pathogen infection success and spore production. We then predicted the effects of each acclimation treatment on rates of host and pathogen population increase by deriving a host's intrinsic growth rate (rm) and a pathogen's basic reproductive number (R0). We found that direct acclimation to warming enhanced a host's heat tolerance and rate of population growth, despite a decline in life-history traits such as lifetime fecundity and lifespan. In contrast, pathogen performance was consistently worse under warming, with within-host pathogen success, and ultimately the potential for disease spread, severely hampered at higher temperatures. Our results suggest that hosts could benefit more from warming than their pathogens, but only by linking multiple individual traits to population processes can the full impact of higher temperatures on host and pathogen population dynamics be realised.

Studying Thermopriming-Mediated Short- and Long-Term Acquired Thermotolerance in Arabidopsis thaliana.

High temperature is one of the most devastating environmental factors that severely impede plant growth multi-laterally and threatens global food security. Global warming and the predicted steady rise in temperature emphasize the urgent need to improve heat stress resilience of crop plants to meet the growing food demand. Although known for several years, a memory-based mechanism termed "priming-induced stress tolerance" or "acquired stress tolerance" has gained the attention of the plant science community in recent years. Thermopriming is one such phenomenon that enhances the plant tolerance to subsequent heat stress and promotes growth. The memory of the foregoing mild increase in temperature is captured and retained as dormant signals, which upon exposure to subsequent high temperature aids in mounting a faster, stronger, and sensitized response. Such acquired thermotolerance is more effective than the basal endurance of the plant due to altered molecular regulatory networks. Thereupon, thermopriming can be used as a convenient tool to study and improve plant response to heat stress. In this chapter, the protocol to study thermopriming-mediated short- and long-term acquired thermotolerance is described in detail.

PtWRKY2, a WRKY transcription factor from Pinellia ternata confers heat tolerance in Arabidopsis.

High temperatures are a major stress factor that limit the growth of Pinellia ternata. WRKY proteins widely distribute in plants with the important roles in plant growth and stress responses. However, WRKY genes have not been identified in P. ternata thus far. In this study, five PtWRKYs with four functional subgroups were identified in P. ternata. One group III WRKY transcription factor, PtWRKY2, was strongly induced by high temperatures, whereas the other four PtWRKYs were suppressed. Analysis of transcription factor characteristics revealed that PtWRKY2 localized to the nucleus and specifically bound to W-box elements without transcriptional activation activity. Overexpression of PtWRKY2 increased the heat tolerance of Arabidopsis, as shown by the higher percentage of seed germination and survival rate, and the longer root length of transgenic lines under high temperatures compared to the wild-type. Moreover, PtWRKY2 overexpression significantly decreased reactive oxygen species accumulation by increasing the catalase, superoxide dismutase, and peroxidase activities. Furthermore, the selected heat shock-associated genes, including five transcription factors (HSFA1A, HSFA7A, bZIP28, DREB2A, and DREB2B), two heat shock proteins (HSP70 and HSP17.4), and three antioxidant enzymes (POD34, CAT1, and SOD1), were all upregulated in transgenic Arabidopsis. The study identifies that PtWRKY2 functions as a key transcriptional regulator in the heat tolerance of P. ternata, which might provide new insights into the genetic improvement of P. ternata.

Stress adaptive plasticity from Aegilops tauschii introgression lines improves drought and heat stress tolerance in bread wheat (Triticum aestivum L.).

Aegilops tauchii is a D-genome donor of hexaploid wheat and is a potential source of genes for various biotic and abiotic stresses including heat and drought. In the present study, we used multi-stage evaluation technique to understand the effects of heat and drought stresses on Ae. tauschii derived introgression lines (ILs). Preliminary evaluation (during stage-I) of 369 ILs for various agronomic traits identified 59 agronomically superior ILs. In the second stage (stage-II), selected ILs (i.e., 59 ILs) were evaluated for seedling heat (at 30 °C and 35 °C) and drought (at 20% poly-ethylene glycol; PEG) stress tolerance under growth chambers (stage-II). Heat and drought stress significantly reduced the seedling vigour by 59.29 and 60.37 percent, respectively. Genotype × treatment interaction analysis for seedling vigour stress tolerance index (STI) identified IL-50, IL-56, and IL-68 as high-performing ILs under heat stress and IL-42 and IL-44 as high-performing ILs under drought stress. It also revealed IL-44 and IL-50 as the stable ILs under heat and drought stresses. Furthermore, in the third stage (stage-III), selected ILs were evaluated for heat and drought stress tolerance under field condition over two cropping seasons (viz., 2020-21 and 2021-22), which significantly reduced the grain yield by 72.79 and 48.70 percent, respectively. Stability analysis was performed to identify IL-47, IL-51, and IL-259 as the most stable ILs in stage-III. Tolerant ILs with specific and wider adaptability identified in this study can serve as the potential resources to understand the genetic basis of heat and drought stress tolerance in wheat and they can also be utilized in developing high-yielding wheat cultivars with enhanced heat and drought stress tolerance.

Strong acclimation effect of temperature and humidity on heat tolerance of the Arctic collembolan Megaphorura arctica.

The Arctic is a highly variable environment in which extreme daily and seasonal temperature fluctuations can occur. With climate change, an increase in the occurrence of extreme high temperatures and drought events is expected. While the effects of cold and dehydration stress on polar arthropods are well studied in combination, little is known about how these species respond to the combined effects of heat and dehydration stress. In this paper, we investigated how the heat tolerance of the Arctic collembola Megaphorura arctica is affected by combinations of different temperature and humidity acclimation regimes under controlled laboratory conditions. The effect of acclimation temperature was complex and highly dependent on both acclimation time and temperature, and was found to have a positive, negative or no effect depending on experimental conditions. Further, we found marked effects of the interaction between temperature and humidity on heat tolerance, with lower humidity severely decreasing heat tolerance when the acclimation temperature was increased. This effect was more pronounced with increasing acclimation time. Lastly, the effect of acclimation on heat tolerance under a fluctuating temperature regime was dependent on acclimation temperature and time, as well as humidity levels. Together, these results show that thermal acclimation alone has moderate or no effect on heat tolerance, but that drought events, likely to be more frequent in the future, in combination with high temperature stress can have large negative impacts on heat tolerance of some Arctic arthropods.

Thermal stressors during embryo incubation have limited ontogenic carryover effects in brook trout.

Winter climate is changing rapidly in northern latitudes, and these temperature events have effects on salmonid thermal biology. Stressors during winter egg incubation could reduce hatching success and physiological performance of fall-spawning fishes. Here we quantified the potential for ontogenic carryover effects from embryonic thermal stress in multiple wild and hatchery-origin populations of brook trout (Salvelinus fontinalis), a temperate ectotherm native to northeastern North America. Fertilized eggs from four populations were incubated over the winter in the laboratory in four differing thermal regimes: ambient stream-fed water, chronic warming (+2 °C), ambient with a mid-winter cold-shock, and short-term warming late during embryogenesis (to stimulate an early spring). We examined body size and upper thermal tolerance at the embryonic, fry (10 weeks post-hatch and 27-30 weeks post-hatch) and gravid adult (age 2+) life stages (overall N = 1482). In a separate experiment, we exposed developing embryos to acute seven-day heat stress events immediately following fertilization and at the eyed-egg stage, and then assessed upper thermal tolerance (CTmax) 37 weeks post-hatch. In all cases, fish were raised in common garden conditions after hatch (i.e., same temperatures). Our thermal treatments during incubation had effects that varied by life stage, with incubation temperature and life stage both affecting body size and thermal tolerance. Embryos incubated in warmer treatment groups had higher thermal tolerance; there was no effect of the mid-winter melt event on embryo CTmax. Ten weeks after hatch, fry from the ambient and cold-shock treatment groups had higher and less variable thermal tolerance than did the warmer treatment groups. At 27-30 post-hatch and beyond, differences in thermal tolerance among treatment groups were negligible. Collectively, our study suggests that brook trout only exhibit short-term carryover effects from thermal stressors during embryo incubation, with no lasting effects on phenotype beyond the first few months after hatch.

ZmNF-YA1 Contributes to Maize Thermotolerance by Regulating Heat Shock Response.

Zea mays (maize) is a staple food, feed, and industrial crop. Heat stress is one of the major stresses affecting maize production and is usually accompanied by other stresses, such as drought. Our previous study identified a heterotrimer complex, ZmNF-YA1-YB16-YC17, in maize. ZmNF-YA1 and ZmNF-YB16 were positive regulators of the drought stress response and were involved in maize root development. In this study, we investigated whether ZmNF-YA1 confers heat stress tolerance in maize. The nf-ya1 mutant and overexpression lines were used to test the role of ZmNF-YA1 in maize thermotolerance. The nf-ya1 mutant was more temperature-sensitive than the wild-type (WT), while the ZmNF-YA1 overexpression lines showed a thermotolerant phenotype. Higher malondialdehyde (MDA) content and reactive oxygen species (ROS) accumulation were observed in the mutant, followed by WT and overexpression lines after heat stress treatment, while an opposite trend was observed for chlorophyll content. RNA-seq was used to analyze transcriptome changes in nf-ya1 and its wild-type control W22 in response to heat stress. Based on their expression profiles, the heat stress response-related differentially expressed genes (DEGs) in nf-ya1 compared to WT were grouped into seven clusters via k-means clustering. Gene Ontology (GO) enrichment analysis of the DEGs in different clades was performed to elucidate the roles of ZmNF-YA1-mediated transcriptional regulation and their contribution to maize thermotolerance. The loss function of ZmNF-YA1 led to the failure induction of DEGs in GO terms of protein refolding, protein stabilization, and GO terms for various stress responses. Thus, the contribution of ZmNF-YA1 to protein stabilization, refolding, and regulation of abscisic acid (ABA), ROS, and heat/temperature signaling may be the major reason why ZmNF-YA1 overexpression enhanced heat tolerance, and the mutant showed a heat-sensitive phenotype.

Melatonin administration during the first half of pregnancy improves physiological response and reproductive performance of rabbits under heat stress conditions.

Context Melatonin may have a heat-stress-alleviating role during pregnancy. Aims To investigate the effects of melatonin administration during the first half of pregnancy on heat-tolerance capacity and pregnancy outputs of naturally heat-stressed rabbits. Methods Forty female rabbits were stratified equally into two experimental groups and daily received 1mg melatonin/kg body weight or not (control) for 15 consecutive days post-insemination. Heat tolerance indices, hormone profile, ovarian structures, and fetal loss were determined. Key results Treatment with melatonin significantly decreased respiration rate and rectal temperature, improved concentrations of nitric oxide, and tended to decrease malondialdehyde concentrations (P =0.064) compared to control. Melatonin treatment significantly increased concentrations of high-density lipoprotein, oestradiol, and progesterone compared to control. No significant differences in the numbers of visible ovarian follicles, corpora lutea, and total implantation sites on day 18 of pregnancy were observed between experimental groups. However, melatonin treatment significantly reduced the number of absorbed implantation sites and significantly improved amniotic fluid volume and conception rate compared to control. Conclusions Melatonin administration during the first half of pregnancy can improve reproductive performance of heat-stressed female rabbits. Implications Melatonin can improve fetal survivability via improving heat-tolerance capacity of does and steroidogenesis.

Acclimation to warming but not hypoxia alters thermal tolerance and metabolic sensitivity in an estuarine crustacean.

Coastal species are challenged by multiple anthropogenic stressors. Plasticity may buffer the effects of environmental change, but investigation has largely been restricted to single-stressor performance. Multistressor studies have often been short-term and relatively less is known about the consequences of plasticity under one stressor for performance under another. Here, we aimed to test for the effects of thermal or hypoxic acclimation on thermal tolerance in the amphipod Gammarus chevreuxi. Animals were chronically exposed to raised temperature or hypoxia prior to determination of upper thermal limits and routine metabolic rate (RMR). Warm acclimation increased all metrics of thermal tolerance, but hypoxic acclimation had no effect. Different responses to the two stressors was also observed for the thermal sensitivity of RMR. Consequently, this species possesses the ability to increase thermal tolerance via plasticity in response to chronic warming but increasing duration of hypoxic episodes will not confer cross-tolerance to a warming environment.

Integrating water balance mechanisms into predictions of insect responses to climate change.

Efficient water balance is key to insect success. However, the hygric environment is changing with climate change; although there are compelling models of thermal vulnerability, water balance is often neglected in predictions. Insects survive desiccating conditions by reducing water loss, increasing their total amount of water (and replenishing it) and increasing their tolerance of dehydration. The physiology underlying these traits is reasonably well understood, as are the sources of variation and phenotypic plasticity. However, water balance and thermal tolerance intersect at high temperatures, such that mortality is sometimes determined by dehydration, rather than heat (especially during long exposures in dry conditions). Furthermore, water balance and thermal tolerance sometimes interact to determine survival. In this Commentary, we propose identifying a threshold where the cause of mortality shifts between dehydration and temperature, and that it should be possible to predict this threshold from trait measurements (and perhaps eventually a priori from physiological or -omic markers).

Genome-wide association study for seedling heat tolerance under two temperature conditions in bread wheat (Triticum aestivum L.).

BACKGROUND: As the greenhouse effect intensifies, global temperatures are steadily increasing, posing a challenge to bread wheat (Triticum aestivum L.) production. It is imperative to comprehend the mechanism of high temperature tolerance in wheat and implement breeding programs to identify and develop heat-tolerant wheat germplasm and cultivars. RESULTS: To identify quantitative trait loci (QTL) related to heat stress tolerance (HST) at seedling stage in wheat, a panel of 253 wheat accessions which were re-sequenced used to conduct genome-wide association studies (GWAS) using the factored spectrally transformed linear mixed models (FaST-LMM). For most accessions, the growth of seedlings was found to be inhibited under heat stress. Analysis of the phenotypic data revealed that under heat stress conditions, the main root length, total root length, and shoot length of seedlings decreased by 47.46%, 49.29%, and 15.19%, respectively, compared to those in normal conditions. However, 17 varieties were identified as heat stress tolerant germplasm. Through GWAS analysis, a total of 115 QTLs were detected under both heat stress and normal conditions. Furthermore, 15 stable QTL-clusters associated with heat response were identified. By combining gene expression, haplotype analysis, and gene annotation information within the physical intervals of the 15 QTL-clusters, two novel candidate genes, TraesCS4B03G0152700/TaWRKY74-B and TraesCS4B03G0501400/TaSnRK3.15-B, were responsive to temperature and identified as potential regulators of HST in wheat at the seedling stage. CONCLUSIONS: This study conducted a detailed genetic analysis and successfully identified two genes potentially associated with HST in wheat at the seedling stage, laying a foundation to further dissect the regulatory mechanism underlying HST in wheat under high temperature conditions. Our finding could serve as genomic landmarks for wheat breeding aimed at improving adaptation to heat stress in the face of climate change.

Reaction-norm animal model analysis of average daily gain heat tolerance in purebred Duroc pigs.

The present study aimed to genetically improve growth performance under high-heat environments by specifically designing a reaction-norm animal model (RNAM) for purebred Duroc pigs in Japan. A total of 54,750 records of average daily gain (ADG) measured for pigs reared at four farms in different prefectures were analyzed. Estimated maximum daily temperatures at the respective farm locations were used to calculate the average cumulative thermal load (TL). The TL values served as an indicator of high-heat environments for pigs. The plausible cumulative period length and threshold temperature for calculating TL were determined to be 8 weeks until just before shipping and 25°C, respectively. Variance components were estimated via RNAM analysis using TL as a linear covariate. The estimated additive genetic variances under both responsive and non-responsive to TL were found to be significant. Moreover, the estimated heritability of ADG ranged from 0.38 to 0.73 for TL values of 0-8. These results suggest that the RNAM developed holds the potential for improving the genetic ability of growth under high-heat environments in pigs.

Thermal tolerance does not explain the altitudinal segregation of lowland and alpine aquatic insects.

Elevation gradients provide powerful study systems for examining the influence of environmental filters in shaping species assemblages. High-mountain habitats host specific high-elevation assemblages, often comprising specialist species adapted to endure pronounced abiotic stress, while such harsh conditions prevent lowland species from colonizing or establishing. While thermal tolerance may drive the altitudinal segregation of ectotherms, its role in structuring aquatic insect communities remains poorly explored. This study investigates the role of thermal physiology in shaping the current distribution of high-mountain diving beetles from the Sierra Nevada Iberian mountain range and closely related lowland species. Cold tolerance of five species from each altitudinal zone was measured estimating the supercooling point (SCP), lower lethal temperature (LLT) and tolerance to ice enclosure, while heat tolerance was assessed from the heat coma temperature (HCT). Alpine species exhibited wider fundamental thermal niches than lowland species, likely associated with the broader range of climatic conditions in high-mountain areas. Cold tolerance did not seem to prevent lowland species from colonizing higher elevations, as most studied species were moderately freeze-tolerant. Therefore, fundamental thermal niches seem not to fully explain species segregation along elevation gradients, suggesting that other thermal tolerance traits, environmental factors, and biotic interactions may also play important roles.

Thermal tolerance of cultured and wild Icelandic arctic charr (Salvelinus alpinus) at self-selected flow rates.

Climate change is predicted to change not only the temperature of many freshwater systems but also flow dynamics. Understanding how fishes will fare in the future requires knowing how they will respond to both extended variations of temperature and flow. Arctic charr have had their thermal tolerance measured, but never with respect to flow. Additionally, this circumpolar species has multiple populations exhibiting dramatic phenotypic plasticity which may mean that regional differences in thermal tolerance are unaccounted for. In Iceland, Arctic charr populations have experienced highly variable flow and temperature conditions over the past 10,000 years. The Icelandic climate, topography and geothermal activity have created a mosaic of freshwater habitats inhabited by charr that vary substantially in both temperature and flow. Our purpose was to test whether populations from these varied environments had altered thermal tolerance and whether phenotypic plasticity of thermal tolerance in charr depends on flow. We raised cultured Icelandic charr from hatch under a 2 X 2 matrix of flow and temperature and compared them to wild charr captured from matching flow and temperature environments. Wild fish were more thermally tolerant than cultured fish at both acclimation temperatures and were more thermally plastic. Icelandic Arctic charr were more thermally tolerant than comparison charr populations across Europe and North America, but only when acclimated to 13 °C; fish acclimated to 5 °C compared equably with comparison charr populations. Icelandic Arctic charr were also more thermally plastic than all but one other salmonine species. Neither flow of rearing or the flow selected during a thermal tolerance (CTmax) test factored into thermal tolerance. Thermal tolerance was also independent of body size, condition factor, heart and gill size. In summary, wild Icelandic Arctic charr have greater thermal tolerance and plasticity than predicted from the literature and their latitude, but artificial selection for properties like growth rate or fecundity may be breeding that increased tolerance out of cultured fish. As the world moves toward a warmer climate and increased dependence on cultured fish, this is a noteworthy result and merits further study.

The carryover effects of embryonic incubation temperature on subsequent growth and thermal tolerance in white sturgeon.

Environmental variation experienced during early periods of development can lead to persistent phenotypic alteration, known as carryover effects. Such effects increase concern for threatened or endangered species such as the white sturgeon (Acipenser transmontanus), particularly considering expected thermal changes due to climate change. We evaluated how temperature during embryonic development affects physiological parameters such as larval and early juvenile growth and thermal tolerance. Nechako River white sturgeon embryos were incubated at different environmental temperatures (Te) of 12 °C (the natural spawning temperature of this population), 15 °C (the hatchery incubation temperature), and 18 °C (representing potential increases in river temperatures given global climate change). After hatch, fish were reared at a common 15 °C for 80 days post-hatch (dph). Individuals from each temperature treatment were tested for thermal tolerance using the critical thermal maximum method (CTmax), euthanized, and measured. Fish were examined at regular intervals from 13 to 80 dph, which bridged the time from the start of exogenous feeding through the transition into early juveniles. We found carryover effects of high embryonic Te in the short term for both thermal tolerance and growth. Fish that developed at 18 °C had the lowest thermal tolerance during the start of exogenous feeding. However, differences in thermal tolerance were small for early juveniles and were unlikely to be ecologically relevant in the longer term. Fish that developed at 18 °C were smallest over the observation period, indicating a possible cost for survival from increasing environmental temperatures during embryonic development. This research represents a window into a critical period of development during which fish are particularly vulnerable to climatic variation, and shows that cooler temperatures (12 °C) during incubation are optimal for this population. The results can inform environmental managers on the best strategies to help conserve current white sturgeon populations across their range.

The temperature sensor TWA1 is required for thermotolerance in Arabidopsis.

Plants exposed to incidences of excessive temperatures activate heat-stress responses to cope with the physiological challenge and stimulate long-term acclimation1,2. The mechanism that senses cellular temperature for inducing thermotolerance is still unclear3. Here we show that TWA1 is a temperature-sensing transcriptional co-regulator that is needed for basal and acquired thermotolerance in Arabidopsis thaliana. At elevated temperatures, TWA1 changes its conformation and allows physical interaction with JASMONATE-ASSOCIATED MYC-LIKE (JAM) transcription factors and TOPLESS (TPL) and TOPLESS-RELATED (TPR) proteins for repressor complex assembly. TWA1 is a predicted intrinsically disordered protein that has a key thermosensory role functioning through an amino-terminal highly variable region. At elevated temperatures, TWA1 accumulates in nuclear subdomains, and physical interactions with JAM2 and TPL appear to be restricted to these nuclear subdomains. The transcriptional upregulation of the heat shock transcription factor A2 (HSFA2) and heat shock proteins depended on TWA1, and TWA1 orthologues provided different temperature thresholds, consistent with the sensor function in early signalling of heat stress. The identification of the plant thermosensors offers a molecular tool for adjusting thermal acclimation responses of crops by breeding and biotechnology, and a sensitive temperature switch for thermogenetics.

Plasticity of Gene Expression and Thermal Tolerance: Implications for Climate Change Vulnerability in a Tropical Forest Lizard.

AbstractTropical ectotherms are thought to be especially vulnerable to climate change because they have evolved in temporally stable thermal environments and therefore have decreased tolerance for thermal variability. Thus, they are expected to have narrow thermal tolerance ranges, live close to their upper thermal tolerance limits, and have decreased thermal acclimation capacity. Although models often predict that tropical forest ectotherms are especially vulnerable to rapid environmental shifts, these models rarely include the potential for plasticity of relevant traits. We measured phenotypic plasticity of thermal tolerance and thermal preference as well as multitissue transcriptome plasticity in response to warmer temperatures in a species that previous work has suggested is highly vulnerable to climate warming, the Panamanian slender anole lizard (Anolis apletophallus). We found that many genes, including heat shock proteins, were differentially expressed across tissues in response to short-term warming. Under long-term warming, the voluntary thermal maxima of lizards also increased, although thermal preference exhibited only limited plasticity. Using these data, we modeled changes in the activity time of slender anoles through the end of the century under climate change and found that plasticity should delay declines in activity time by at least two decades. Our results suggest that slender anoles, and possibly other tropical ectotherms, can alter the expression of genes and phenotypes when responding to shifting environmental temperatures and that plasticity should be considered when predicting the future of organisms under a changing climate.

Short-term dietary teprenone improved thermal tolerance and mitigated liver damage caused by heat stress in juvenile largemouth bass (Micropterus salmoides).

Heat stress seriously threatens fish survival and health, demanding immediate attention. Teprenone is a gastric mucosal protective agent that can induce heat shock protein expression. This research investigated the effects of teprenone on largemouth bass (Micropterus salmoides) subjected to heat stress. Juvenile fish were assigned to different groups: group C (control group, 0 mg teprenone/kg diet), T0, T200, T400, and T800 (0, 200, 400, and 800 mg teprenone/kg diet, respectively), which were fed for 3 days, followed by a day without the diet. All groups except group C were subjected to acute heat stress (from 24 °C to 35 °C at 1 °C per hour and then maintained at 35 °C for 3 h). The results were as follows: The critical thermal maxima were significantly higher in the T200, T400, and T800 groups compared with the T0 group (P < 0.05). Heat stress caused severe damage to the tissue morphology of the liver, while teprenone significantly reduced this injury (P < 0.05). Serum cortisol concentration decreased gradually as teprenone concentration increased, and the lowest concentration was observed in the T800 group (P < 0.05). Compared with the T0 group, the serum activities of aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase were significantly lower in the T200, T400, and T800 groups (P < 0.05). The liver activities of catalase, total superoxide dismutase, and peroxidase were significantly higher in the T200 group than in the T0 group (P < 0.05). Transcript levels of the heat shock proteins (hsp90, hsp70, hspa5, and hsf1) and caspase family (caspase3 and caspase9) in the liver of the T200 group were significantly higher than those of the T0 group (P < 0.05). Western blot results showed that HSP70 and HSPA5 in the liver were significantly upregulated in the T200 group compared with the T0 group (P < 0.05). In summary, dietary teprenone improved thermal tolerance, alleviated heat stress damage in the liver, enhanced antioxidant capacity, and upregulated heat shock proteins in juvenile largemouth bass. This study offers theoretical support for applying teprenone in aquaculture to reduce financial losses caused by abiotic factors.